The disclosure relates to films for use in protecting substrate surfaces during manufacturing, storage, transport or use. The disclosure also relates to a method for making the films.
Surface protection films, also known as masking films, are typically used to provide a physical barrier to prevent damage, contamination, scratching, scuffing, or other marring of a substrate. Masking films may be used to provide such protection during manufacture, shipping, or storing prior to use of the substrate, for example. Such films may be used in numerous applications as protective coverings for surfaces, particularly for protecting relatively smooth surfaces, such as acrylics, polycarbonates, glass, polished or painted metals and glazed ceramics. Optical substrates for televisions, monitors, and other displays, for example, require masking films that both protect the surface and may be removed without damaging, leaving residues of an adhesive, or other contaminants or particulates on the surface.
Traditionally, masking films have comprised corona-treated films or adhesive-coated paper or film. Corona-treated films are films that have been exposed to an electrostatic discharge to oxidize the surface of the film. This oxidation increases the film's surface tension and attraction to polar surfaces. Such corona-treated films typically are smooth films and rely on very precise corona treatment to facilitate adhesion. Unless embossed, corona-treated films are typically subject to wrinkling, which makes it difficult to use and handle the films. A further disadvantage is that the adhesion promoting effects of corona treatment dissipate with time.
Generally, conventional masking films are relatively difficult to use and handle. Because masking films are designed to adhere to a surface, they may also adhere to themselves when the masking film is wound on a roll or the adhesion surface otherwise contacts a portion of the masking film. Blocking, as it is called, may result in processing difficulties including delays and wasted material. To reduce the tendency for self adherence, masking films may be coated with a weak adhesive. The weak adhesive on the masking film may prevent the film from adhering tightly to itself on the roll, however, the weak adhesive may also not provide sufficient adherence to the surface to be protected.
Other films may be provided with one matte surface opposite the adhesion surface; often called one side matte (“OSM”) masking films. The irregularity of a matte surface does not provide a good surface for adhesion and provides antiblocking properties to the masking film.
There is a need for a masking film that has a low self adherence but provides sufficient adherence to a substrate to provide suitable protection. There is a further need for a masking film that has a cushioning effect and eases handling of flat substrates.
In other applications, it may be desired to use materials that do not adhere to the surface, but instead are interleaved with the substrates to provide a physical separation. Such applications are commonly used in manufacturing operations where, for example, optical grade glass or plastic substrates are tacked together. In such applications, paper or other materials are used to interleave with the substrates to protect against damage. The interleaving sheets are also used between stacked fragile and scratch sensitive substrates and to provide separation between very smooth optical substrates during shipment to end users.
Accordingly, there is also a need for low cost, non-adhering materials for use in protecting substrate surfaces.